1. Technical Field
The present disclosure relates to a circuit device, an oscillator, an electronic apparatus, a moving object, and the like.
2. Related Art
A temperature compensated oscillator called a temperature compensated crystal oscillator (TCXO) is known. The TCXO is used as a reference signal source in, for example, a portable communication terminal, a GPS related apparatus, a wearable apparatus, an on-vehicle apparatus, or the like.
The TCXO includes an ATCXO which is an analog temperature compensated oscillator and a DTCXO which is a digital temperature compensated oscillator. An example of an ATCXO is disclosed in JP-A-2012-199631. An example of a DTCXO is disclosed in JP-A-64-82809.
Since an oscillator, such as a TCXO, requires extremely high frequency accuracy, a power supply having characteristics, such as low noise and low temperature characteristics, is used. In an analog oscillator, such as an ATCXO, a linear regulator of a low drop-out (LDO) system is used as an external power supply. An internal power supply circuit can be constituted of a linear regulator of an LDO system which uses an output of a bandgap reference circuit as a reference voltage. In such a circuit configuration, while a power supply having low noise and low temperature characteristics is obtained, reduction in power consumption is difficult. For example, a linear regulator used as an external power has a power consumption larger than a switching regulator. If a switching regulator is used as an external power supply, since power consumption can be lowered but has noise larger than that of the linear regulator, an internal power supply circuit requires a high power supply rejection ratio (PSRR). The bandgap reference circuit used in the internal power supply circuit is difficult to maintain in a high PSRR when current consumption decreases, and it is difficult to reduce power consumption in a low noise condition.